Although the primary sensory pathways largely preserve modality (and even submodality) specificity, much of the brain is devoted to a convergence of the different sensory modalities. It is through this sensory convergence that stimulus complexes can take on a significance that will supersede the individual modalities and stimulus components. Our long-term objective has been to understand how the brain integrates multiple sensory cues to (1) produce a comprehensive awareness of the environment and (2) facilitate appropriate responses to external stimuli. Our more immediate objective was to use the superior colliculus (SC) as a model structure because of the multiple sensory inputs it receives and the extensive documentation that already exists concerning its organization and behavioral involvements. It has, in fact, proved to be ideal for our purposes and much of what is proposed here uses this model. During the last grant period, we made significant advances toward understanding the fundamental spatial and temporal principles by which individual SC cells integrate multisensory information. This provided a basis for accurately predicting the responses of SC cells when presented with multiple stimuli from different sensory modalities and some of the overt behaviors believed to be dependent of the circuitry of the SC. Most of the experiments proposed here are a direct outgrowth of the data generated during the last grant period. One of the first objectives is to determine whether the spatial and temporal principles now known to govern multisensory integration differ from those governing unimodal integration and whether these principles are independent of the specific neural structure examined. These data are essential to understand whether there is a single set of integrative principles in the CNS that supersedes structure and sensory modality. Similarly, we will evaluate how closely the behaviors dependent on multisensory integration parallel the electrophysiology of our model cells. One of the most intriguing observations made during the last grant period is that the alignment of the peripheral sensory organs produces the spatial coincidence of multisensory receptive fields on which multisensory integration is based. Yet movement of these peripheral organs during normal behavior can misalign the registry among receptive fields of different modalities. Thus, we will examine the consequences of this misalignment on the functional properties of SC cells and the behaviors dependent on their activity.